【初中英语知识】:什么是主语从句

发布时间:2020-12-29 19:12:13 阅读数:
摘要: 主语从句是从句在复合句中充当主语成分的句子。引导主语从句的词有从属连词that、whether以及连接代词who、what、which、whoever、whatever、whichever和连接副词when、where、why、how等,连词位于句首不能省略。...

 主语从句是从句在复合句中充当主语成分的句子。引导主语从句的词有从属连词that、whether以及连接代词who、what、which、whoever、whatever、whichever和连接副词when、where、why、how等,连词位于句首不能省略。

初中英语知识,初中英语,什么是主语从句

  一、引导词

  1. 引导词that与what

  what既有引导主语从句的作用,同时又在从句中作句子成分(主语、宾语、表语等)。这时what相当于all that/everything that...,常译成"所……的(东西、事情、话等.)",而that只起连接作用,本身无实际意义,在从句中也不担当任何句子成分。但that引导的主语从句放在句首时,不能省略that。

  例句:What is done can't be undone.

  (谚语)已成定局,无可挽回。

  What we can't get seems better than what we have.

  我们得不到的东西似乎比已得到的要好。

  2. 引导词if和whether

  if和whether引导动词后的宾语从句时一般可通用,但介词后的宾语从句、主语从句(放在句首时)、表语从句常由whether引导。

  例句:Whether she will go home or not is unknown.

  她是否回家还不得而知。

  3. 其它引导词

  连接代词who、which、whom、whose有各自的意义,起连接作用,并在从句中充当语、宾语、表语、定语等;连接副词when、where、why、how等有各自的意义,起连接作用,并在从句中充当状语。

  例句: When they will start has not been decided yet.

  他们何时出发还没决定。

  二、引导词it

  上述例句中的主语从句都是放在句首,但有时为了使句子结构平衡,避免"头重脚轻",常用it作形式主语,而把从句放在后面。

  例句:It depends on the climate whether they are going shopping today.

  他们是否今天去购物还得看天气情况。

  这样就构成了一些以It开头的常用句型,具体如下:

  1. It is + adj. / n. +从句。

  It is a pity/shame that... 遗憾的是……;

  It is possible that... 很可能……;

  It is unlikely that... 不可能……;

  2. It +不及物动词+从句。

  It seems/appears that... 似乎……;

  It happened that... 碰巧……;

  3. It + be +过去分词+从句。

  It is said that... 据说……;

  It is known to all that... 众所周知……;

  It is reported that... 据报道……;

  It is believed that... 据信……;人们相信……;

  It is suggested that... 有人建议……;

  It must be pointed out that... 必须指出……;

  It has been proved that... 已证明…….;

  例句:It is believed that at least a score of buildings were damaged or destroyed.

  据信,至少有二十座楼房遭到破坏或彻底毁掉。

  It is suggested that the meeting should be put off.

  有人建议会议延期召开。

  It's reported that three people were killed in the accident and five were hurt badly.

  据报道,事故中三人丧生,五人重伤。